I thought the non O (which is acquired in country) and the 12 month extension of stay were essentially the same thing? Are they not? What is the difference?
Your other option is to pay a visa service if you meet neither of the criteria I listed above but it will most likely cost you in excess of $1,000 USD. I hear Key Visa in South Pattaya has one of the lower fees for this service in Pattaya. Good luck!
I'm not a big proponent of using agents but in this situation I believe it's the wisest route. I've seen many posts in the past where people are exasperated after having gone to bank after bank only to be turned down every time. If I were you, I would hire an agent the day after I arrived. I hear it costs about 3K THB but I think it would be 3K well spent. If you are in Pattaya, I've heard good things about Mots Services and Key Visa. You can find them both on FB. Also, Bangkok Bank is one of the banks (maybe the only bank) that will receive foreign transfers above 50K THB and will document the transaction as income from outside of Thailand (this can be very important at some immigration offices.) Below is a screen shot from Wise (money transfer service) from when I send over my monthly pension. Details matter here and can be the difference between being approved or denied and ending up having to hire an agent to acquire you a visa, at a hefty price. Good luck!!